Magnetic tape file protect system

ABSTRACT

A spring-loaded cylinder of the same diameter as the magnetic tape file protect ring is mounted on the transport reel hub assembly so that the cylinder will be spring-loaded its maximum distance from the transport front panel when the file protect ring is absent and is pressed back towards the panel when the file protect ring is present. A light and photocell are used to monitor the position of the cylinder. The photocell output then becomes the file protect signal for the using system.

States atent Whysong et a1.

[54] MAGNETIC TAPE FILE PROTECT SYSTEM [72] Inventors: Dale C. Whysong,Falls Church; Dale E. Leininger, Fairfax, both of [73] Assignee: GeneralKinetics Inc., Reston, Va.

[22] Filed: Sept. 2, 1970 [21] Appl. No.: 69,182

[52] US. Cl. ....340/267 R, l79/100.2 D, 250/219 R, 250/222 R, 340/1741B, 340/282 [51] Int. Cl. ..G08b 21/00 [58] Field of Search ..242/36, 57;179/1002 D; 340/1741 13, 282, 267 R; 250/222 R, 219 R [56] ReferencesCited UNITED STATES PATENTS 1,988,255 1/1935 Soons ..250/219 R 1 Aug.29, 1972 2,761,017 8/1956 Camras ..l79/l00.2 D 3,474,753 10/1969 Weyrichet 21].. 179/1002 D X 3,564,155 2/1971 Pendleton ..l79/l00.2 D

Primary Examiner-David L. Trafton Attorney-Cushman, Darby & Cushman [57]ABSTRACT A spring-loaded cylinder of the same diameter as the magnetictape file protect ring is mounted on the transport reel hub assembly sothat the cylinder will be spring-loaded its maximum distance from thetransport front panel when the file protect ring is absent and ispressed back towards the panel when the file protect ring is present. Alight and photocell are used to monitor the position of the cylinder.The photocell output then becomes the file protect signal for the usingsystem.

4Claims,2DrawingFigures BACKGROUND OF THE INVENTION Magnetic recordingtape transport device file protect systems used previously are basicallyof two types. One type feels for the file protect ring of the computerreel and upon detecting the ring withdraws the feeling probe andelectrically locks the file protect signal into the system. A secondtype has a mechanical probe which rides against the file protect ringcontinuously. Both types are expensive to manufacture and consist ofmechanical parts which wear out and are expensive to replace. The secondtype is the least reliable because the probe constantly riding on theturning reel quickly wears the bearings of the probe wheel.

One prior art system is described in IBM Customer Engineering ReferenceManuals, for instance, that for the IBM 2401 Models 2 and 3 computerunder various headings including File Protection and Relay NFPl Mostcomputer tape transport manufacturers, if not all, employ techniquessimilar to the IBM system. Some do not retract the feeler probe at allbut allow it continually to contact the tile protect ring. This is badpractice since both the file protect rings and the feeler probes wearrapidly while the wheel rotates and the feeler probe scrapes smallparticles of plastic dust from the file protect ring. These particlesthen become contaminants which drift onto the recording tape surface andproduce errors in reading and writing the tape.

The device disclosed in the U.S. Pat. No. of Cheney, 3,199,093 issuedAug. 3, 1965, includes a magnetic reed switch which senses proximity toa removable mumetal ring on the tape reel to permit or prevent erasure.An object stated by the patentee is the elimination of need forfrictional contact between the sensor and the part being sensed.

The following patents show the use of various mechanical probes forsensing the presence or absence of a file protect ring or similarelement on a magnetic tape reel.

2,466,514 Vagtborg April 5, 1949 2,594,848 Begun April 29, 19522,761,017 Camras August 28, 1956 3,145,944 Pendleton August 25, 19643,199,091 Barkhuff et a1. August 3, 1965 3,259,712 Libby July 5, 19663,335,410 Baskin et al. August 8, 1967 3,417,387 Rayfield December 17,1968 3,474,753 Weyrich et al. October 28, 1969 In the US. Pat. No. ofBrenner, 3,109,604, a photoelectric sensor is used to adjust the tensionapplied to tape being wound. The tape itself enters into the sensingprocess and no file protect system is disclosed.

SUMMARY OF THE INVENTION and photocell are used to monitor the positionof the cylinder. The photocell output then becomes the file protectsignal for the using system. This technique eliminates fatigue-pronecomponents of other systems. With the use of long-life bulbs 5,000 hoursof use can be expected before the bulb needs replacing, and bulbs areeasily and inexpensively replaced.

The principles of the invention will be further hereinafter discussedwith reference to the drawing wherein a preferred embodiment is shown.The specifics illustrated in the drawing are intended to exemplify,rather than limit, aspects of the invention as defined in the clause.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a longitudinal sectional view of a tape transport reel driveassembly equipped with a file protect system in accordance with theprinciples of the invention, a reel containing a file protect ring beingabout to be installed on the assembly.

FIG. 2 is a view of the apparatus of FIG. 1 after installation of thering-containing reel on the assembly.

DISCUSSION OF THE PRESENT LY PREFERRED EMBODIMENT OF THE INVENTION Aconventional drive mounting panel is depicted at 10 having an openingwhich receives a shaft 12. Behind the panel a conventional drive pulley14 is mounted on the shaft. In front of the panel, a transport reel hub16 is mounted on the shaft 12. The hub 16 is conventional excepting thatan annular spring 18, e.g., of beryllium copper is mounted, e.g., byscrews 20, on the rear face of the hub 16 so that its outer peripheralregion 22 normally lies spaced behind the rear face of the hub 16. Inaddition a sensing collar 24 in the form of an axially short tubularmember 26 is provided, having an internal flange 28 intermediate itsaxial extent. Normally, the sensing collar is mounted so that theshoulder 28 is resiliently gripped between the rear face of the hub 16and the peripheral region 22 of the spring 18. In such disposition, theinner end region 30 of the collar 24 lies spaced a short distance X infront of the panel 10 and the outer end region 32 of the collar 24 liesa short distance Y forwardly of the reel abutment surface 34 of the hub16. The inner peripheral surface 36 of the end region 32 lies adjacentthe outer periphery of the disk shaped portion 38 of the hub whose frontsurface constitutes the reel abutment surface 34. The end surface 40 ofthe end region 32 lies in such axial disposition as to be freelyreceived in the file protect ring receiving groove G of the standardreel R when the tile protect ring P is removed (i.e., not present) butto engage the file protect ring P when it is in place. The engagementbegins as the reel is being pushed home on the hub 16, i.e., before therear face of the reel has abutted the reel abutment surface 34. In thissecond instance, pushing the reel further onto the hub causes thesensing collar to be moved axially rearwardly against resilient forceoffered by the spring 18 peripheral region 22 until the forward endsurface 40 of the collar front end region 32 lies in the substantiallysame plane as the abutment surface 34 (i.e., the distance Y has beenreduced to zero).

It should now be noticed that the system disclosed further includes asignal emitter 44 and a signal sensor 46 both mounted on the front ofthe drive mounting panel. The two elements 4 3, 36 are spaced from butaimed toward one another on opposite sides of an axially rearwardprojection of the sensing collar inner end region 30 on the drivemounting panel 10.

The configurations are such that when the file protect ring is absentfrom a reel mounted on the hub, the collar 24 is in its rest positionand the two elements 44, 46 are in unobstructed communication, but whenthe file protect ring is present in the groove of a reel mounted on thehub, the collar 24 is displaced rearwardly sufficiently that its rearportion 30 obstructs, i.e., blinds, communication between the twoelements Mi and 46.

in the preferred embodiment depicted, the signal emitter is an electriclight and the signal sensor is a photocell. The locations of the twodevices may be physically interchanged and equivalent sensors andemitters based on emission and reception of energy of other wavelengthsor types (e.g., ultrasound) may be substituted.

One might ask whether failure of the photocell to see the light couldambiguously indicate either of two circumstances: the presence of thefile protect ring P or that the light 44 had burned out. However, inpractice, the electrical current for the light is supplied via the samecircuit that enables the write circuit C so that if the light bulb burnsout, writing cannot be enabled. Writing is enabled only when thefollowing conditions are present simultaneously: the collar 24 isaxially deflected rearwardly by the presence of a file protect ring P inthe groove G of the reel R mounted on the hub 16 and the light bulb isnot burned out.

Preferably, long-life light bulbs having about 5,000 hours of life areused.

Note that because the collar 24 rotates with the hub and reel that thereis no rubbing contact to produce wear and contaminating particles.

Note further that when a reel having a file protect ring is removed fromthe hub, the spring peripheral portion 22 in seeking to return to a lessstressed state will move the collar 26 axially forwardly from theposition shown in FIG. 2 to the one shown in FIG. 1.

As an alternative, the file protect system can be set up so that abilityof the photocell (or other sensor) to see the light (or other emitter)makes writing possible. This can be done by moving the light andphotocell sufficiently out from the drive mounting panel that the rearend region 30 of the collar 24 normally lies between the light and thephotocell. In such instance the region 30 is provided with an axiallynarrow, circumferentially extending band of openings through which thephotocell can see the light upon axially rearward displacement of thecollar caused by contact of the front end of the collar with the fileprotect ring P on a reel R.

it should now be apparent that the file protect system as describedhereinabove possesses each of the attributes set forth in thespecification under the heading Summary of the Invention hereinbefore.Because the file protect system of the invention can be modified to someextent without departing from the principles of the invention as theyhave been outlined and explained in this specification, the presentinvention should be understood as encompassing all such modifications asare within the spirit and scope of the following claims.

What is claimed is:

l. in a tape transport system wherein a tape reel having a face groovedto removably receive a file protect ring the reel being removablymounted on a transport hub having a surface abutted by the reel facewhen the reel is properly positioned on the hub, an improved fileprotect system including:

a file protect ring sensing member;

means mounting said sensing member on the hub for limited axial movementthereon between one extreme wherein a forward portion the sensing memberprotrudes forwardly of the reel face abutted surface of the hub andanother extreme wherein said forward portion of the sensing memberprotrudes forwardly to a lesser extent, whereby said sensing memberextends rearwardly to a first, lesser extent in said one extreme and toa second, greater extent in said other extreme;

said mounting means resiliently disposing said sensing member towardsaid first extreme, but allowing said sensing member to be forced,against resilient disposition, from said one extreme to the other;

the forward portion of said sensing member being configured and disposedin axial alignment with the location of the groove of the grooved faceof the reel to freely enter the groove when the file protect ring isabsent from the groove and to encounter the file protect ring when thefile protect ring is present in the groove, whereby when the reel,without a file protect ring, is mounted on the hub and abutted againstthe hub surface, the forward portion of the sensing member freely entersthe groove and the sensing member remains disposed in the first extremeand whereby when the reel, with a file protect ring, is mounted on thehub and abutted against the hub surface, the forward portion of thesensing member encounters the tile protect ring whereupon the sensingmember is forced back to the other extreme thereof;

a signal emitter;

a signal sensor adapted to sense signals emitted by said signal emitteronly when the sensor is in unobstructed communication with the emitter;

said signal emitter and said signal sensor being disposed on oppositesides of an axially rearward projection of said sensing member at suchan axial disposition that, in a first instance, when said sensing memberis in a first of its one and other extremes, the signal emitter andsignal sensor are in unobstructed communication and, in a secondinstance, when said sensing member is in a second of its one and otherextremes, the signal emitter and signal sensor are blocked fromunobstructed communication;

said signal sensor being adapted to be interposed in a write-enablecircuit to permit writing in only one of said first and secondinstances.

2. The improved file protect system of claim 1 wherein the signalemitter is an electric light and the signal sensor is a photocell.

3. The improved file protect system of claim 1 wherein the sensingmember comprises a tubular collar circumscribing the hub and havingmeans defining a radially inwardly directed flange thereon intermediatethe axial extent thereof. Said mounting means comprising an annular flatspring mounted on the hub and having an outer peripheral portiontrapping said radially inwardly directed flange against the rear of thehub.

4. In a tape transport system which includes a writeenable circuit and arotatable hub for removable receiving a tape reel, and improved fileprotect system for use with tape reels having removably received fileprotect rings in grooves thereon, the improved file protect systemcomprising:

a sensing member mounted on said hub for rotation therewith;

means resiliently biasing the sensing member forwardly so that, if atape reel being mounted on the hub has no file protect ring, the sensingmember will enter the tape reel groove, but if the tape reel beingmounted on the hub has a file protect ring in the groove thereof, thesensing member will engage and be pushed rearwardly against restoringforce provided by said resiliently biasing means; alight;

a photocell incorporated in said write enable circuit, said light andsaid photocell being so mounted with respect to said sensing member,that when the sensing member is positioned forwardly, the lightilluminates the photocell and when the sensing member is positionedrearwardly because it has engaged a file protect ring, the light isobstructed by the sensing member from illuminating the photocell.

1. In a tape transport system wherein a tape reel having a face groovedto removably receive a file protect ring the reel being removablymounted on a transport hub having a surface abutted by the reel facewhen the reel is properly positioned on the hub, an improved fileprotect system including: a file protect ring sensing member; meansmounting said sensing member on the hub for limited axial movementthereon between one extreme wherein a forward portion the sensing memberprotrudes forwardly of the reel face abutted surface of the hub andanother extreme wherein said forward portion of the sensing memberprotrudes forwardly to a lesser extent, whereby said sensing memberextends rearwardly to a first, lesser extent in said one extreme and toa second, greater extent in said other extreme; said mounting meansresiliently disposing said sensing member toward said first extreme, butallowing said sensing member to be forced, against resilientdisposition, from said one extreme to the other; the forward portion ofsaid sensing member being configured and disposed in axial alignmentwith the location of the groove of the grooved face of the reel tofreely enter the groove when the file protect ring is absent from thegroove and to encounter the file protect ring when the file protect ringis present in the groove, whereby when the reel, without a file protectring, is mounted on the hub and abutted against the hub surface, theforward portion of the sensing member freely enters the groove and thesensing member remains disposed in the first extreme and whereby whenthe reel, with a file protect ring, is mounted on the hub and abuttedagainst the hub surface, the forward portion of the sensing memberencounters the file protect ring whereupon the sensing member is forcedback to the other extreme thereof; a signal emitter; a signal sensoradapted to sense signals emitted by said signal emitter only when thesensor is in unobstructed communication with the emitter; said signalemitter and said signal sensor being disposed on opposite sides of anaxially rearward projection of said sensing member at such an axialdisposition that, in a first instance, when said sensing member is in afirst of its one and other extremes, the signal emitter and signalsensor are in unobstructed communication and, in a second instance, whensaid sensing member is in a second of its one and other extremes, thesignal emitter and signal sensor are blocked from unobstructedcommunication; said signal sensor being adapted to be interposed in awriteenable circuit to permit writing in only one of said first andsecond instances.
 2. The improved file protect system of claim 1 whereinthe signal emitter is an electric light and the signal sensor is aphotocell.
 3. The improved file protect system of claim 1 wherein thesensing member comprises a tubular collar circumscribing the hub andhaving means defining a radially inwardly directed flange thereonintermediate the axial extent thereof. Said mounting means comprising anannular flat spring mounted on the hub and having an outer peripheralportion trapping said radially inwardly directed flange against the rearof the hub.
 4. In a tape transport system which includes a write-enablecircuit and a rotatable hub for removable receiving a tape reel, andimproved file protect system for use with tape reels having removablyreceived file protect rings in grooves thereon, the improved fileprotect system comprising: a sensing member mounted on said hub forrotation therewith; means resiliently biasing the sensing memberforwardly so that, if a tape reel being mounted on the hub has no fileprotect ring, the sensing member will enter the tape reel groove, but ifthe tape reel being mounted on the hub has a file protect ring in thegroove thereof, the sensing member will engage and be pushed rearwardlyagainst restoring force provided by said resiliently biasing means; alight; a photocell incorporated in said write enable circuit, said lightand said photocell being so mounted with respect to said sensing member,that when the sensing member is positioned forwardly, the lightilluminates the photocell and when the sensing member is positionedrearwardly because it has engaged a file protect ring, the light isobstructed by the sensing member from illuminating the photocell.